GB2082087A

GB2082087A - A process of treating metal handling and shaping devices

Info

Publication number: GB2082087A
Application number: GB8115700A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-13
Filing date: 1981-05-21
Publication date: 1982-03-03
Also published as: US4289804A; GB2082087B

Abstract

A process of treating metal handling and shaping devices consists of cleaning the devices to the bare metal, applying a liquid suspension of at least 5% to 25% submicron sized particles of graphite to said bare metal of the devices to penetrate the metal and build up smooth adhering and lubricating coating on said metal devices with sufficient excess of graphite to form a smooth surface. The size of the submicron particles of graphite are no larger than 5m mu as determined by electron microscopy.

Description

SPECIFICATION A process of treating metal handling and shaping devices This invention relates to processes for treating metal handling and shaping devices such as steel forging dies and ingot molds.

It is desirable to provide a process for building up a penetrating coating on forging dies and the like with a material that is not affected by the heat of the metal shaping operation and to which foreign materials will not adhere. The material used in the process desirably forms a penetrating lubricating adhesive coating on the metal handling devices.

The prior art comprises my U.S. Patents Nos.

4,187,334 and 4,187,335, issued February 5, 1980.

According to the invention there is provided a process of treating metal handling and shaping devices which comprises the steps of cleaning said devices to the bare metal, penetrating a liquid suspension of submicron sized particles of graphite into said bare metal of the devices, said liquid suspension including at least 5% to 25% submicron sized particles of graphite, applying enough of said liquid suspension of graphite to build up smooth adhering and lubricating coating on said metal portions and building up sufficient excess of graphite on said devices to form a smooth surface, the size of said submicron particles of graphite being no larger than 5mF as determined by electron microscopy.

A process embodying the invention comprises the coating of the devices as by spraying or other application of a material which is essentially sub micron sized particles of graphite in an improved liquid carrier of the extremely fine size of the submicron sized particles of graphite which lowers the surface tension of the liquid carrier and enables the graphite particles to penetrate the metal surfaces of the devices and build up a smooth adhering coating thereover.The liquid carrier may comprise water, an aqueous sodium silicate solution and hydrochloric acid, a water soluble resin of the carboxyl group of carboxylic acids, either COOH or CO2H and/or composed of a carboxyl group and a hydroxyl group, ("carboxyl; oxatyl, carboxy, the acidic COOH group, it determines the basicity of an organic acid"), such as carboxy polymethylene polymers as a dry fluffy acid powder which is power mixed with the submicron sized graphite particles and the liquid carrier to obtain a suitable hydrogen bonding in the solution.

A suspension which is particularly suitable for building up penetrating and lubricating adhesive coatings on metal handling and shaping devices and comprises between about 5% to 25% by weight sub-micron sized particles of graphite, between about 34% to 75% of a solution of water and sodium silicate (Na2Si307), wherein the sodium silicate is present at about 40% of the solution, between about 2% to 10% concentrated hydrochloric acid of a 90% purity by weight, between about 33% to 75% of a solution of water and a carboxy polymethylene polymer resin wherein the resin is present in amounts between 1% to 10% of the solution by weight, and between about 15% to 20% water by weight.

The critical particle size of the submicron sized graphite particles being substantially amicron; less than 5moor 5 x 10-7 cm preferably as determined by electron microscopy. The submicron sized graphite particles are made by ball milling the finest mesh colloidal graphite particles commercially available for a time sufficient to obtain the desired sub micron graphite particle size which eliminates the platelets.

The carboxy polymethylene polymer resin powder has a specific gravity of 1.41 and a bulk density of 13 Ibs. per cubic foot (20.8 gm/cc). It is available as "CARBOPOL" from B.F. Goodrich Chemical Co. and low concentrations mixed with water as herein disclosed produce a thin gel-like liquid with penetrating and adhesive qualities.

The liquid carrier as set forth hereinbefore comprises an effective wetting agent which contributes to the ability of the sub micron sized particles of graphite to penetrate the metal of the metal handling and shaping devices.

The lower percentages of the submicron sized particles of graphite in the liquid carrier perform most effectively when a number of applications of the material are applied and when only one or a few applications of the materials are applied to the metal surfaces, higher percentages of the submicron sized particles of graphite are more desirable.

In either case the critical particle size of the graphite in the material penetrates the metal surfaces being treated and builds up an extremely smooth coating to which the metal being handled or shaped will not adhere.

In using the material disclosed herein, the process involves mixing the materials to form a liquid suspension of the submicron sized particles of graphite and then spraying the same by any suitable spraying equipment on cleaned metal surfaces of the metal handling and shaping devices to be treated. One or more coatings are applied as necessark to build up a smooth unbroken surface of the material on the metal devices being treated and the material may be applied to the metal surfaces while they are either hot or cold.

Ingot molds are advantageously treated with the material and such treatment expedites the stripping of ingots from the molds. Specific suspension compositions which may be used are given in the following Examples A to D.

A. Substantially 8% by weight submicron sized particles of high purity synthetic graphite, substantially 7% by weight concentrated hydrochloric acid of substantially 90% purity, substantially 18% by weight water (H2O), substantially 34% by weight aqueous sodium silicate solution wherein the Na2Si307 is present at about 40% by weight of the solution and substantially 33% by weight water soluble carboxy polymethylene polymer resin as a powder wherein the resin is present at substantially 8% by weight of the solution.

B. Substantially 8% by weight submicron sized particles of high purity synthetic graphite, substantially 7% by weight concentrated hydrochloric acid of substantially 90% purity, substantially 18% by weight water (H2O), substantially 67% by weight aqueous sodium silicate solution wherein the Na2Si307 is present at about 40% by weight of the solution.

C. Substantially 8% by weight submicron sized particles of high purity synthetic graphite, substantially 7% by weight concentrated hydrochloric acid of substantially 90% purity, substantially 18% by weight water (H2O), substantially 67% by weight aqueous solution of carboxy polymethylene polymer resin as a powder wherein the resin is present at substantially 8% by weight of the aqueous solution of carboxy polymethylene polymer resin as a powderwherein the resin is present at substantially 8% by weight of the aqueous solution.

An alternative liquid carrier has been found to produce a suitable suspension of the submicron sized particles of graphite and substitutes xanthan gum for the resin, the gum is a natural high molecular weight linear polysaccharide, functioning as a hydrophilic colloid to maintain the submicron sized particles of graphite in suspension and contribute to the penetrating lubricating adhesive coating as described hereinbefore.

A specific example of such an alternative material follows: D. Substantially 8% by weight submicron sized particles of high purity synthetic graphite, substantially 7% by weight concentrated hydrochloric acid of substantially 90% purity, substantially 18% by weight water (H2O), substantially 67% by weight aqueous solution of xanthan gum as a powder wherein the gum is present at substantially 8% by weight of the aqueous solution.

Variations in the amounts of xanthan gum may be used as from 1% to 19% of the aqueous solution.

The treatment of ingot molds hereinbefore referred to by the process and with the material disclosed herein obtains the desired results by reason of the very fine sized graphite of the material and the manner of the application. Specifically it is known in the art that molten steel in an ingot mold takes carbon from the metal of the ingot mold thereby adversely affecting the interior of the mold by removing the portions thereof and it is also known that when this occurs the stripping of the cooled ingot from the mold becomes more difficult because of the interlock obtained between the solidified metal and the irregular surface of the mold.By heating an ingot mold the grain structure enlarges and the porosity of the metal increases and in the present process the material is preferably applied to the ingot mold when it is heated as by spraying or dipping the heated mold in the liquid suspension material. Under such conditions the submicron sized particles of graphite aided by the liquid carrier penetrates the metal surfaces of the ingot mold which have been previously cleaned and build up a smooth lubricating and adhering coating which being largely graphite which is able to supply the carbon that molten steel usually absorbs from the ingot mold.

Thus the treating material is sacrificed to some degree and the inner surface of the ingot mold is retained in its desirable smooth condition. Stripping ingots from the smooth inner surface of the mold is thus considerably expedited and the molds last considerably longer as the carbon from the metal of the molds is not sacrificed as has heretofore been common in the art.

Claims

1. A process of treating metal handling and shaping devices which comprises the steps of cleaning said devices to the bare metal, penetrating a liquid suspension of submicron sized particles of graphite into said bare metal of the devices, said liquid suspension including at least 5% to 25% submicron sized particles of graphite, applying enough of said liquid suspension of graphite to build up smooth adhering and lubricating coating on said metal portions and building up sufficient excess of graphite on said devices to form a smooth surface, the size of said submicron particles of graphite being no larger than 5my as determined by electron microscopy.

2. A process according to Claim 1, wherein several penetrating coatings of said liquid suspension of submicron sized particles of graphite are applied to said metal devices successively.

3. A process according to Claim 1, wherein several penetrating coatings of said liquid suspension of submicron sized particles of graphite are sprayed on said metal devices successively

4. A process according to Claim 1, wherein the devices are heated to a temperature at which the grain structure expands and the porosity of the metal increases and wherein the liquid suspension of submicron sized particles of graphite is applied to the heated device.

5. A process according to any preceding Claim wherein the liquid suspension includes sodium silicate.

6. A process according to any one of Claims 1 to 4, wherein the liquid suspension includes a water soluble resin of the carboxyl group of carboxylic acids.

7. A process according to any one of Claims 1 to 4, wherein the liquid suspension includes carboxy polymethylene polymer resin and sodium silicate.

8. A process according to any one of Claims 1 to 4, wherein the liquid suspension includes xanthan gum and sodium silicate.

9. A process according to any one of Claims 1 to 4, wherein the liquid suspension includes xanthan gum and carboxy polymethylene resin.

10. A process according to any one of Claims 1 to 4wherein the liquid suspension includes xanthan gum.

11. A process of treating metal handling and shaping devices, substantially as hereinbefore de- -f scribed with reference to the Examples,